In the first mechanical optical switches such as that described by P. G. Hale and R. Kompener in the journal "Electronics Letters" page 388, vol. 12 No. 15, July 22, 1976, the moving end of the optical fiber was not guided in its stroke but was solely manoeuvered by means of a magnetic sleeve attracted magnetically towards one or other of diametrically opposite inside corners of a square section tube having the fixed ends of two other fibers resting therein. In this type of switch the lack of guidance for the moving optical fiber means that it is not possible to obtain the necessary accuracy in the alignment and in the gap between the fibers for obtaining a low attenuation coefficient.
Since then, other types of optical switch have been proposed in which the moving optical fiber end is guided in its motion by a magnetizable flexible blade to which it is glued either in a structure derived from the structure of a reed relay (such as the switches described in British Pat. No. 1 426 475) or else using a structure derived from a flexible armature electromagnetic relay, such as the switches described in French patent application No. 2 380 568.
Such structures improve the accuracy of the movement of the moving optical fiber end and its coefficient of attenuation, as well as its uniformity over time, however the coefficients of attenuation obtained are not of the same order as those obtained in single junction couplers since it is not possible to accurately adjust the alignment and the gap between the ends of the fibers.
In an attempt to solve this problem, proposals have been made, in particular in French patent application No. 2 384 276, to guide the moving optical fiber end by means of flexible magnetic blades without fixing it to said blades, thereby enabling the fiber length to be subsequently adjusted and consequently adjusting the gap between the moving fiber end and the fixed fiber end. This adjustment suffers from the drawback of being common for both positions and consequently of being a compromise. In addition, the movement of the moving fiber is no longer as accurate as it would be if its end were glued.
The aim of the present invention is to provide an optical mechanical switch providing optical coupling with low attenuation in each of its positions.